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Checks here against useracc are not useful and are racy.

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copyin/copyout are sufficient to guard against bad addresses. They will return
EFAULT if the user is up to no good (by choice or ignorance). There's no point
in checking, since it doesn't even improve the error messages.

Noticed by: jhb
Reviewed by: brooks, jhb
This commit is contained in:
Warner Losh 2020-04-13 21:04:33 +00:00
parent 450a2e2a12
commit ab485b018a
1 changed files with 0 additions and 30 deletions
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30
sys/cam/scsi/scsi_pass.c
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@ -1232,15 +1232,6 @@ passcopysglist(struct cam_periph *periph, struct pass_io_req *io_req,
user_watermark += len_to_copy;
kern_watermark += len_to_copy;
if (!useracc(user_ptr, len_to_copy,
(direction == CAM_DIR_IN) ? VM_PROT_WRITE : VM_PROT_READ)) {
xpt_print(periph->path, "%s: unable to access user "
"S/G list element %p len %zu\n", __func__,
user_ptr, len_to_copy);
error = EFAULT;
goto bailout;
}
if (direction == CAM_DIR_IN) {
error = copyout(kern_ptr, user_ptr, len_to_copy);
if (error != 0) {
@ -1445,20 +1436,6 @@ passmemsetup(struct cam_periph *periph, struct pass_io_req *io_req)
if (io_req->lengths[i] == 0)
continue;
/*
* Make sure that the user's buffer is accessible
* to that process.
*/
if (!useracc(io_req->user_bufs[i], io_req->lengths[i],
(io_req->dirs[i] == CAM_DIR_IN) ? VM_PROT_WRITE :
VM_PROT_READ)) {
xpt_print(periph->path, "%s: user address %p "
"length %u is not accessible\n", __func__,
io_req->user_bufs[i], io_req->lengths[i]);
error = EFAULT;
goto bailout;
}
tmp_buf = malloc(lengths[i], M_SCSIPASS,
M_WAITOK | M_ZERO);
io_req->kern_bufs[i] = tmp_buf;
@ -1561,13 +1538,6 @@ passmemsetup(struct cam_periph *periph, struct pass_io_req *io_req)
} else
io_req->user_segptr = io_req->user_segs;
if (!useracc(*data_ptrs[0], sg_length, VM_PROT_READ)) {
xpt_print(periph->path, "%s: unable to access user "
"S/G list at %p\n", __func__, *data_ptrs[0]);
error = EFAULT;
goto bailout;
}
error = copyin(*data_ptrs[0], io_req->user_segptr, sg_length);
if (error != 0) {
xpt_print(periph->path, "%s: copy of user S/G list "